I have a big plastic case by SKB that I bring on the boat. I take 4 cameras (Canon's professional top of the line model) on the water each with a different lens, and they all sit like sardines in the box. It has a rubber seal, and I can flop it closed and that keeps out the spray and waves. I can work very quickly with this system, and I keep a few rags to wipe the cameras if they get a little wet. I bring a separate waterproof bag for clothes, food, water, and anything else. The box is just for the cameras.